It is the purpose of this proposal to develop a human lymphoblast cell line (transformed human lymphocyte) for the analysis of the human genome. This includes using the characteristic phenotypes of the lymphoblast as non-selective markers and the isolation of mutants that are resistant to the inhibition of the normal amino acids; mutant that would facilitate the selection of the individual human chromosomes in human x mouse or human x Chinese hamster hybridization experiments. The amino acid resistant mutants will be used to initiate a study of the mechanism of amino acid transport and regulation. The analysis of amino acid inhibition of growth (amino acid antagonisms) in the lymphoblast, a comparison of the lymphocyte and the lymphoblast with regard to the relative concentration of amino acids in the intracellular pool, the ability of these two cell types to accumulate different amino acids in the absence and presence of other amino acids will enable us to determine the significance of amino acid antagonism on the growth of these two cell types and therefore its significance to the malignant transformation.